add cooldown to message pruning

chain/messagepool/config.go

@@ -1,6 +1,8 @@
 package messagepool
 
 import (
+	"time"
+
 	"github.com/filecoin-project/lotus/chain/types"
 )
 
@@ -8,6 +10,7 @@ var (
 	ReplaceByFeeRatioDefault  = 1.25
 	MemPoolSizeLimitHiDefault = 30000
 	MemPoolSizeLimitLoDefault = 20000
+	PruneCooldownDefault      = time.Minute
 )
 
 func (mp *MessagePool) GetConfig() *types.MpoolConfig {
@@ -29,5 +32,6 @@ func DefaultConfig() *types.MpoolConfig {
 		SizeLimitHigh:     MemPoolSizeLimitHiDefault,
 		SizeLimitLow:      MemPoolSizeLimitLoDefault,
 		ReplaceByFeeRatio: ReplaceByFeeRatioDefault,
+		PruneCooldown:     PruneCooldownDefault,
 	}
 }

chain/messagepool/messagepool.go

@@ -91,6 +91,9 @@ type MessagePool struct {
 	// pruneTrigger is a channel used to trigger a mempool pruning
 	pruneTrigger chan struct{}
 
+	// pruneCooldown is a channel used to allow a cooldown time between prunes
+	pruneCooldown chan struct{}
+
 	blsSigCache *lru.TwoQueueCache
 
 	changes *lps.PubSub
@@ -215,6 +218,7 @@ func New(api Provider, ds dtypes.MetadataDS, netName dtypes.NetworkName) (*Messa
 		pending:       make(map[address.Address]*msgSet),
 		minGasPrice:   types.NewInt(0),
 		pruneTrigger:  make(chan struct{}, 1),
+		pruneCooldown: make(chan struct{}, 1),
 		blsSigCache:   cache,
 		sigValCache:   verifcache,
 		changes:       lps.New(50),
@@ -226,6 +230,9 @@ func New(api Provider, ds dtypes.MetadataDS, netName dtypes.NetworkName) (*Messa
 		rbfDenom:      types.NewInt(RbfDenom),
 	}
 
+	// enable initial prunes
+	mp.pruneCooldown <- struct{}{}
+
 	if err := mp.loadLocal(); err != nil {
 		log.Errorf("loading local messages: %+v", err)
 	}
@@ -249,6 +256,8 @@ func (mp *MessagePool) Close() error {
 }
 
 func (mp *MessagePool) Prune() {
+	// this magic incantation of triggering prune thrice is here to make the Prune method
+	// synchronous:
 	// so, its a single slot buffered channel. The first send fills the channel,
 	// the second send goes through when the pruning starts,
 	// and the third send goes through (and noops) after the pruning finishes

chain/messagepool/pruning.go

@@ -23,7 +23,17 @@ func (mp *MessagePool) pruneExcessMessages() error {
 		return nil
 	}
 
-	return mp.pruneMessages(context.TODO(), ts)
+	select {
+	case <-mp.pruneCooldown:
+		err := mp.pruneMessages(context.TODO(), ts)
+		go func() {
+			time.Sleep(mp.cfg.PruneCooldown)
+			mp.pruneCooldown <- struct{}{}
+		}()
+		return err
+	default:
+		return xerrors.New("cannot prune before cooldown")
+	}
 }
 
 func (mp *MessagePool) pruneMessages(ctx context.Context, ts *types.TipSet) error {

chain/types/mpool.go

@@ -1,6 +1,8 @@
 package types
 
 import (
+	"time"
+
 	"github.com/filecoin-project/go-address"
 )
 
@@ -9,6 +11,7 @@ type MpoolConfig struct {
 	SizeLimitHigh     int
 	SizeLimitLow      int
 	ReplaceByFeeRatio float64
+	PruneCooldown     time.Duration
 }
 
 func (mc *MpoolConfig) Clone() *MpoolConfig {